Sherlock Has an Oral Fixation
by wendymarlowe
Summary: Sherlock had an oral fixation - that was the only possible explanation for why he found so many bloody excuses to put things in his mouth. John is not as good at hiding his fascination as he thought.
1. Chapter 1

Sherlock had an oral fixation. That was the only possible explanation for why he found so many bloody excuses to put things in his mouth. John grimaced as he watched his flatmate extend his tongue to delicately lick the dead woman's purse.

"Doesn't that contaminate the crime scene?"

Sherlock snorted dismissively. "It's hardly going to ruin anything the Yard would have actually tested. Alkaline taste, though - not bleach, would have smelled that, but she put this purse down somewhere that had been recently cleaned with industrial-strength chemicals without added odors. Seems obvious she was inside the building at the time of the murder."

Lestrade frowned. "Her purse tastes bitter, so she's our killer?"

"Not remotely, and do try to keep up," Sherlock snapped. "She was _inside_. As was someone who was cleaning. Find your housekeeper and you'll find your murderer. Based on the dead man's office, I'd say he was dodgy about getting out paychecks on time, and seems the type to have been handsy as well. This woman was just collateral damage - witness, perhaps." He turned on his heel and swooped away from the body, coat billowing out behind him. "That's all you need from me - come on, John."

John and Lestrade shared a commiserating look before John gave up and trotted obediently after him.

* * *

><p>The licking thing was really getting out of hand. John could ignore Sherlock nibbling on pens, pencils, toothpicks, and the like, but it was bloody hard to concentrate on his book when Sherlock had microscope slides strewn all over the kitchen and was <em>licking <em>each one in turn.

"Should I even ask what you're doing?"

Sherlock looked up, startled out of whatever-it-was he was experimenting on. "Thinking," he said.

"Looked like you're slobbering on your microscope slides, to me."

"Experiment."

"Ah. Of course." John shot him a tight smile and tried to focus on his book again.

"Residual effects of various brands of chewing gum and breath freshener on saliva samples over time . . ." Sherlock trailed off, staring at John. "Oh. _Oh_."

"What?" John glanced down to see if there was something wrong with his clothing. But no, nothing out of place-

"I'm bothering you," Sherlock said.

"Hey, when you're in a strop, you complain that my breathing offends you," John countered. "I hardly think you're one to talk."

"No, the - the licking thing. It bothers you."

_"Bother" isn't the word I'd use . . ._ John shrugged instead. "A bit unsanitary, perhaps, but I'm not touching your microscope anyway. None of my business."

"You watch me. When I'm thinking and I chew on my fingertips."

John shrugged again. He couldn't really deny that - Sherlock did have a habit of tenting his hands under his chin as he thought, usually when he was flopped any which way on the sofa, and he often ended up resting his front teeth on his fingers. Sometimes he had both pointer fingers inside his mouth, all the way to the second knuckle, and when he drew them back out again they'd be red with tooth marks and shiny with saliva. He had such a glorious mouth, mobile and expressive, and John tried very hard not to think about what else Sherlock might like to jam in there.

And that was the problem, wasn't it? John tried not to notice, tried not to think about Sherlock that way, but Sherlock stuck things in his mouth _all the bloody time_ and never seemed to have the slightest bit of shame about it. If anything, he reveled in the tastes and sensations - for someone who ate as little as Sherlock did, it was astounding how often he managed to find excuses to lick or suck on or nibble on things. John could hardly be blamed if he started daydreaming about that expressive mouth.

Not that he was _gay_, by any means. Gay would indicate he was interested in other men too, right? Being straight was comfortable, it was normal, it was expected. And if John happened to have a _thing _for Sherlock's mouth, that didn't necessarily mean he was _gay_. Sherlock just had . . . a particularly gorgeous mouth. _Fuckable_, John's brain helpfully supplied, and he squirmed in his seat.

Sherlock, of course, noticed, and abandoned his experiment to come sit in his armchair a few feet away. "Fascinating," he murmured.

John tried very hard to ignore him, keeping his eyes strictly downward on his book.

"I am aware I use my mouth more than most people," Sherlock said quietly. "I think better when I suck on things."

John could feel his face flame, but if he could just pretend long enough, Sherlock might drop it-

"I'm told I'm rather good at it, actually," Sherlock continued. He ducked his head so he could make eye contact even though John steadfastly refused to look up. "I've had the most amazing epiphanies, given the right things to suck on."

"Right then." John slammed his book closed. "I'm going upstairs."

Sherlock said nothing, just stared after him with calculating eyes and his lower lip caught artfully between his teeth in a way that made John suddenly very glad he was wearing somewhat baggy trousers. He escaped up to his room, flopped face-down on his bed, and groaned.


	2. Chapter 2

"You want me to fellate your penis."

John nearly fell out of bed in his scramble to turn the lamp on. For most of his life he'd been an extremely light sleeper, but that had changed after Afghanistan - apparently now Sherlock could sneak into his room and stand at the foot of his bed in just his boxers without waking him up.

"Jesus, Sherlock," he groaned. A glance at the alarm clock showed it was just after 3 AM. "Why are you here?"

"You want me to fellate you," Sherlock repeated. "I've been thinking about it and I've decided I want to."

Right. So apparently dreams got even stranger after waking up. "For an experiment?" It was the first thing John could think of. A stupid question, he knew immediately, which was confirmed by Sherlock's eyeroll.

"No need to be obtuse, John," he said. "Of course I'll be collecting data about what stimuli work best for your body, but it's not for a case. I've just decided autofellatio isn't worth the effort when you're right here anyway."

"You've just . . ." John's brain was struggling to keep up. "Wait, you can _do _that?"

In answer, Sherlock flopped onto the bed next to John and curled his upper body an impressive hundred and eighty degrees. The movement put his head in the general vicinity of his hips - it certainly couldn't have been comfortable, but maybe with some further contortions-

Sherlock lay back and shot John a half-smirk. "It's better than manual stimulation, but the main advantage is I can have something in my mouth when I come. I don't know that I'd define myself as having an actual fixation or fetish, but I'm very aware this fits the 'freak' label as well."

"It's not that," John protested immediately. "I'm not - I mean, I'm not going to judge you for - well, whatever you do to get off. It's none of my business. And I don't think you're a freak. I'm just . . ." He scrubbed a hand over his face. "Yeah, still not all the way awake yet, sorry. I don't do my best thinking at 3 AM."

"Would an orgasm help?" Sherlock rolled away from him to throw back the covers, revealing John's holey gray t-shirt and plain cotton boxers. "It may take me a few minutes to hone in on how you like it, but-"

"Sherlock, stop." John pulled the covers back up over his hips, hiding the erection which was already very much in evidence. "This is . . . a bit not good, okay? Bloody surreal, at any rate." He resisted the urge to curl up into a little fetal ball right there on the bed, rampant erection protected against any encroachment, no matter what the erection in question might think about the situation. "Flatmates don't _do _this," he finished weakly.

"_I'm _your flatmate, and I would very much like to 'do this,' so I doubt the validity of your data. I'd be sucking you off already if you weren't protesting so much," Sherlock countered. "Is it because I'm a man? Because I know for a fact that you enjoy fellatio when a woman performs it."

"Not going to ask how you'd know that 'for a fact.' And it's not because . . ." John closed his eyes and groaned. "Fuck it. Why did you have to bring this up in the middle of the night?"

"Because that's when I made the decision to perform fellatio on you. Do try to keep up." Sherlock bit his lip in an entirely practiced move which nonetheless had the predictable effect on John's cock. "You don't want me to make you come in my mouth? I know you've thought about it."

"That doesn't mean I want to actually _do _it." John immediately realized what that meant - what he had implicitly admitted - and frantically tried to backpedal. "Not that I'm admitting to-"

"Fine." Sherlock reached down and tugged off his own pants, revealing a nicely-proportioned cock which was already most of the way to hard. "You don't have to participate, then - I'll just do this myself."

"Sherlock-"

"Nonsense, you didn't want it so now I'll just have to come in my own mouth. And I'm going to do it here and you're welcome to watch or join in or go right back to sleep and ignore me. Whatever." He palmed himself roughly, cradling his bollocks in one hand and his shaft in the other, and folded his spine in half again so his glans was pressed right up against his lips. "Observe," he murmured, and stretched forward that last little bit so the tip of his cock slid into his mouth.

_Fuck. Fuckityfuckfuckfuckfuck_. John's mouth actually went dry as he watched Sherlock slip his lips up and down his own shaft, gaining an inch or two of penetration before having to retreat. A groan burst from the detective's throat, loud and low, and John heard an answering moan come from his own mouth. It was _wrong _and awkward and looked uncomfortable as hell, and all the willpower in the world couldn't have prevented John from reaching down and squeezing his own erection in time with Sherlock's thrusts. He looked so sinfully tempting, totally nude, all long, lean angles and that wild riot of dark hair bobbing up and down in rhythm with the little turned-on sounds he was making and _bloody hell _John was so hard he was liable to pass out.

"Take off your pants, John," Sherlock purred from around the head of his own cock. "It's not like they're hiding anything."

John was getting naked even before his brain finished acknowledging that yes, Sherlock was probably right, and the fact that John was wanking right alongside him didn't help any. The dingy t-shirt and the boxers ended up somewhere on the floor, or wadded up in the closet, or possibly flung onto the windowsill, but it didn't matter because Sherlock was uncurling like a lazy housecat and draping himself across John's bare legs with his head in John's lap. He didn't touch, not immediately, but he did have his eyes locked onto John's cock and his mouth was loose and open and inviting and John only barely held himself back from hitching up his hips and driving into that welcome opening.

"May I?" Sherlock let out a warm breath, opening his jaw wide, and . . . _fuck, I've never been good at telling him "no" anyway_. John groaned and jolted his hips forward.

Sherlock's lips encompassed him immediately, warm and wet and sinfully mobile. There was no hesitation, no easing into it - one moment they weren't touching, the next Sherlock's cheeks were hollowed out against John's shaft and his tongue was jabbing delicately at John's frenulum and the suction was enough to have John seeing stars. Sherlock practically _purred _and insinuated himself further into John's lap.

"Oh God, that's-"

"Mmmmmph," Sherlock growled from around John's cock, not backing off even an inch to speak. "Dop dalking. Douch me."

John didn't need to be asked twice - his hands tangled in Sherlock's curls of their own volition, tracing the movement of Sherlock's scalp as he bobbed his head up and down. It felt like the whole world had suddenly gone all warped and stretched out, a fisheye lens of sensation focused squarely on Sherlock's sinfully warm mouth. Sherlock squirmed a bit more, settling himself heavily over John's legs and casually rutting against John's ankle, and it was all John could do not to whimper.

This was better than anything he could have fantasized about. Hell, even just seeing Sherlock totally nude exceeded expectations - surely the man had an embarrassing birthmark, or a little extra pudge somewhere, or odd scars? But no, Sherlock's back was an endless canvas of pale skin as he writhed, running his hands over John's hips and thighs and abdomen and _fuck_, John wanted to see more of him . . .

_Well why not? _John surveyed their respective positions, calculated the available space on the mattress, then locked his legs around Sherlock's slim chest and flipped them both over in one smooth movement. The shift in positions forced Sherlock to let go, to suck in a quick breath and blink up at his ex-army flatmate (_forgot that, Sherlock, did you?)_, but one look at John's face had him falling still and his eyes going wide.

"I can't reach you down there," John explained, even as he rotated himself a hundred and eighty degrees on the bed so his face was in the general area of Sherlock's groin. "This is more efficient, don't you think?"

Sherlock's reply, if there was one, was cut off by a muffled curse as John closed the last few inches and nibbled a not-all-that-gentle bite mark into the crease at the top of Sherlock's right thigh. Sherlock went totally still for a few moments, then lunged forward and swallowed down John's cock in a renewed burst of energy.

It was . . . it was . . . right, so John's brain was having trouble with language skills too, but Sherlock smelled like soap and sweat and pre-ejaculate and John had never particularly found the smell of bollocks to be a good thing before, but now he could probably spend hours just breathing in that musky smell and teasing Sherlock with little nips and licks right there, right where the skin was hot and flushed and hairy and not at all feminine, no, not there where Sherlock's bollocks transitioned back into ordinary skin, and what would his cock taste like? John hesitated, the last vestiges of _not gay not gay not gay_ echoing in his head, but then Sherlock executed a particularly delicious oral maneuver around his own cock and fuck it, it was all just biology and Sherlock's biology was ludicrously tempting.

He expected - well, he wasn't sure what he expected, but smooth and silky and just plain _skin _wasn't it. No sweat glands there, nothing to detract from the warm texture of engorged veins just below the surface as John licked an exploratory stripe up the underside of Sherlock's cock. There was a burst of flavor near the tip - salty? bitter? Not entirely unfamiliar, John had certainly smelled and tasted his own come enough times to know what it was like (not on purpose, really, but puberty is puberty), but not off-putting either.

Sherlock was making the most amazing sounds though, now, long drawn-out moans and obscene slurping noises as he worked John's cock right to the brink. They were both leaking - obviously Sherlock was just as turned-on by sucking John off as he was by John nosing around at his own erection.

There was probably less than a minute left before John had to make the decision: reciprocate, or just give Sherlock a hand job? Maybe a little of both? The relentless suction of Sherlock's mouth and the motion of his roving hands over John's thighs and stomach and arse made it hard to think - but fuck, he had to do _something_-

He chickened out and settled for a combination, mouthing Sherlock's shaft with sloppy kisses while fondling the head with one hand. The tension was ratcheting up inside him, but he could tell from the bunching of Sherlock's abdominal muscles that the feeling was mutual. Sherlock was moaning, a muffled litany of incomprehensible curses and pleas and something that may have been French. John slid his free hand around behind Sherlock's bollocks and squeezed gently, pressing an insistent fingertip against Sherlock's perineum-

Sherlock came apart in a spectacular flurry of shouts and tense limbs and with John's cock jammed so far down his throat John could have sworn he could could feel Sherlock's epiglottis. Warm spurts of semen drenched John's hand, and then Sherlock hummed a blissfully tranquil sigh and the vibration was the final thing John needed to tip over that edge himself. Sherlock kept up the warm suction until John was completely spent and limp against him, then languidly sat up enough to rotate in place so they were both lying the wrong way around with their feet on John's pillow and Sherlock could press against him from shoulder to knee.

"Should have known you'd be incredible," Sherlock mumbled into the hair at the nape of John's neck.

_How the hell is he even able to talk right now?_ John made a vague noise which was supposed to indicate agreement and sank further into the mattress. The self-doubt took a long time in coming, but it finally showed up just in time for John to shake off the last of the post-coital haze.

Really was no way to interpret their actions as anything other than gay, was there? John may not have been all that well-versed in this aspect of things, but he was pretty sure pulling a 69 with your very male flatmate in the dead of night, naked in your bed, fit that definition to a T. A very warm, very languid _T_, who was currently draped across John in a tangle of long limbs and sharp elbows and gentle huffs of breath against the back of John's neck.

"Did it meet your expectations?" Sherlock asked, his voice a low rumble in John's ear.

"I - wasn't expecting anything. Didn't expect that. Expected to just sleep tonight, I guess," John explained.

"Liar," Sherlock retorted, and leaned forward to nip at John's exposed earlobe. "You've been watching my mouth for ages. You just never dragged your precious sexuality into it until tonight."

"I've . . . I guess I've spent a lot of time being determinedly _not gay_. It's taking some adjustment. Gonna take me a bit to think through it all."

Sherlock propped himself up on one elbow and curled around so he could press a kiss onto John's lips. "If I may make a suggestion? I've got a fantastic trick I've found that really helps me when I need to think . . ."


End file.
